This invention relates to a method, apparatus and compositions for inhibiting the ability of mosquitoes to locate or track a human body by scent detection. More particularly, the invention relates to the use of certain compounds in compositions and apparatus to inhibit mosquitoes"" ability to detect humans by scent detection.
Compounds, compositions and formulations for protecting human beings from being bitten by mosquitoes are known in the art. Generally, these compounds, compositions and formulations are based on their ability to persist on the skin of the person upon topical or surface application for a time sufficient to repel mosquitoes. Numerous adjuvant materials have been added to mosquito repellants to increase the persistence of the repellents to the skin of a person. However, despite the various attempts to improve the repelling activity of the known mosquito repellents, these attempts have generally not been successful, as almost anyone who has used such mosquito repellents can attest.
Thus, the art has been searching for new and more effective repelaents against mosquitoes. However, the search for more effective mosquito repellents has not generally been met with success since most mosquito repellents have been found only to possess a limited degree of repellency and are generally not particularly effective. There is, therefore, a need for more effective means to deter mosquitoes from locating and biting humans and other targets such as livestock. Moreover, this need has recently become more acute and urgent because mosquitoes have been discovered to be carriers of significant diseases that can be passed on to a target by the mosquitoes biting the target. A further need is to be able to reduce the use of environmentally unfriendly pesticides.
The inventors have discovered that compounds, compositions and formulations heretofore proposed as repellents for mosquitoes have lacked the necessary efficacy due to the ability of mosquitoes to locate and be drawn to the targets by olfactory emissions of the target. Thus, if a mosquito enters a zone or space where a potential target is located, the mosquito can be attracted to the target by olfactory emissions of the target and, this olfactory attraction is sufficient to overcome any repellency activity of the repellent compound, composition or formulation applied on the target. Therefore, the present invention provides compositions and formulations containing compounds usable in methods and apparatus for inhibiting the olfactory target tracking abilities of mosquitoes when an effective amount of the inhibiting compound(s) is/are dispersed in a three dimensional atmospheric space.
According to this invention, the ability of mosquitoes to locate a target is inhibited by dispensing into a spatial area an inhibiting effective amount of at least one inhibiting compound selected from the group consisting of 3-methyl-1-alkene-3-ols of the formula: 
and 3-methyl-1-alkyn-3-ols of the formula: 
wherein R1 and R2 are each independently a saturated or unsaturated aliphatic hydrocarbon group containing from 1 to about 12 carbon atoms.
The inhibiting compound can be dispensed into the three dimensional atmospheric space by any suitable means sufficient to provide an inhibiting effective amount of the inhibiting compound(s). Such dispensing means includes, for example, evaporation, atomization and ionic dispersion of the inhibiting compound from any suitable composition or formulation. Such composition or formulation will generally comprise a base vehicle containing at least one of the inhibiting compounds.
The inventors have discovered that if an effective amount of at least one inhibiting compound selected from the group consisting of 3-methyl-1-alkene-3-ols of the formula: 
and 3-methyl-1-alkyn-3-ols of the formula: 
wherein R1 and R2 are each independently a saturated or unsaturated aliphatic hydrocarbon group containing from 1 to about 12 carbon atoms is dispensed into the atmosphere of a three dimensional environmental space, the ability of mosquitoes to locate and track a target, such as humans or livestock, by the target""s olfactory emissions is inhibited.
Any suitable 3-methyl-1-alkene-3-ols or 3-methyl-1-alkyn-3-ol of the formulas may be employed in the method, compositions and apparatus of this invention. Especially suitable inhibiting compounds are nerolidol, 3-methyl-1-octen-3-ol, linalool and dehydrolinalool. Depending on the particular mosquito species, either the 3-methyl-1-alkyn-3-ols or the 3-methyl-1-alkene-3-ols are better inhibitors than the other class of components and will be preferred for that species of mosquito. The inhibiting compounds may be utilized singly or as mixtures of two or more of such compounds.
Any suitable inhibiting effective amount of the inhibiting compound(s) may be employed. Such inhibiting effective amounts can include amounts, based on the square footage of land or base surface area of the environmental area to be treated, within the range of from about 0.000005 g/hr/ft2 to about 0.004 g/hr/ft2, preferably amounts within the range of from about 0.00015 g/hr/ft2 to about 0.0002 g/hr/ft2, and especially an amount of about 0.00016 g/hr/ft2.
The inhibiting compounds for use in this invention may be provided in an essentially pure form of the inhibiting compounds or as a component of a natural essential oil having a concentration of an inhibiting compound sufficient to make it practical and feasible to dispense an inhibiting effective amount of inhibiting compound. Generally, the essential oil will contain a concentration of the inhibiting compound of at least about 2%, preferably at least about 5%, and especially at least about 50% by weight. For example, the inhibiting compound can be provided as a synthetically produced, essentially pure compound or as a component of an essential oil such as basil oil, ho wood oil and the like.
The inhibiting compounds of this invention, or essential oils containing such inhibiting compounds, may be employed in any formulation suitable for dispensing inhibiting effective amounts of the compounds. The compounds will generally be employed in formulations comprising a suitable vehicle containing the inhibiting compounds. For example, the inhibiting compound can be formulated in a specially formulated wax-like medium or vehicle engineered to release desired amounts of vaporous inhibiting compound at ambient temperatures, such as those mediums or vehicles available from Koster Keunen of Watertown, Conn. An example of such a wax-like medium available from Koster Keunen is known as Insect Repellent Wax Bar No. 9, which is a blend of waxes having the following general composition: fatty acids ranging in carbon chain length of from C16 to C22, fatty alcohols ranging in carbon chain length of from C16 to C22, paraffinic hydrocarbons ranging in carbon chain length of from C19 to C47, branched hydrocarbons ranging in carbon chain length of from C23 to C69, beeswax and other natural waxes such as candelilla and carnauba. The wax mixture will generally be formulated with concentrations of the inhibiting compounds of this invention ranging from about 20% to 60% and the formulation has a congealing point which may vary from about 75xc2x0 C. to about 45xc2x0 C. Alternatively, the inhibiting compound can be formulated in a porous medium or vehicle suitable for releasing effective amounts of the inhibiting compound. As an example of such porous medium or vehicle is a polyester membrane material having micropores encasing a block of inhibiting compound saturated fibers that gradually releases the inhibiting compound so that it permeates the microporous membrane and is released to the environment. Such porous membrane known as World of Fragrance(trademark) cups is available from Waterbury Companies, Inc. of Waterbury, Conn.
The formulations can be placed in any suitable container or device for dispensing the inhibiting compound. For example, the formulations can be placed in a suitable fan-equipped device so that one can obtain, for example, fan-driven evaporation of the inhibiting compound from a porous medium or wax-like medium containing the inhibiting compound. As examples of such fan-equipped devices, there can be mentioned the devices disclosed in U.S. Pat. No. 5,370,829 of Waterbury Companies, Inc. and the apparatus disclosed in U.S. Pat. No. 5,799,436 of Biosensory Insect Control Corporation, each of said patents being incorporated herein by reference thereto.
Another suitable means of dispensing the inhibiting compound is by atomization and/or ionic dispersion of the compound as suitable-sized, positively-charged droplets from a suitable atomization or ionic dispersing apparatus, such as the Ionic Wind(trademark) device, available from Brandenburg, Ltd. of Brierery Hill, United Kingdom.
The inhibiting compounds of this invention are effective against mosquitoes, such as for example, Aedes taeniorhyncus (Black Salt Marsh mosquito), Culex nigripalpus, Aedes aegypti, Aedes albpictus (Asian Tiger mosquito), Culex pipiens (common house mosquito) and the like.